Global coronavirus infections topped nine million on Monday as the World Health Organization warned that the pandemic was accelerating and Saudi Arabia said it would allow a "very limited" number of pilgrims to the hajj next month.

France took its biggest step yet back to normality by allowing millions of children to return to school.

But despite Europe further easing lockdowns, cases are still rising around the world, especially in Latin America with Brazil now registering more than 50,000 deaths.

And there are fears of new clusters in Melbourne and Lisbon as well as renewed outbreaks in Beijing and other parts of Asia.

"The pandemic is still accelerating," WHO's director general Tedros Adhanom Ghebreyesus told a virtual health forum organised by Dubai in the United Arab Emirates.

Tedros said the greatest threat facing the world was not the virus itself, which has now killed over 465,000 people and infected nine million, but "the lack of global solidarity and global leadership."

"We cannot defeat this pandemic with a divided world," he said. "The politicisation of the pandemic has exacerbated it."

Brazilian President Jair Bolsonaro has repeatedly played down the threat, comparing the virus to a "little flu" and arguing the economic impact of shutdowns is worse than the virus itself.

Brazil is the second worst-affected country behind the United States, where the number of deaths topped 120,000 on Monday and political infighting has prevented a unified policy.

Mexico, Peru and Chile are also coping with severe crises -- Mexico City being forced to delay plans for a broad reopening of the economy as the country's death toll raced past 20,000.

With a vaccine still far away, the WHO has called for a rapid increase in production of the steroid dexamethasone, which has been shown to have life-saving potential for critically ill patients.